Gas powered burner with perforated ceramic elements

ABSTRACT

The invention discloses a gas powered burner with perforated ceramic elements which are adjustable in their planes and/or essentially perpendicular to their planes. The burner dan be adjusted so as to emit uniform infra-red radiation with good precision within the wavelength band, irrespective of how the burner is angled or located.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention concerns a gas powered burner, emitting substantiallyinfrared radiation, with perforated ceramic elements which areadjustable in and/or perpendicular to their planes.

Infrared is used nowadays in many different areas. Common weaknesses ofexisting gas powered constructions are:

1. Sensitivity to position. Existing constructions function adequatelyas long as they are horizontally mounted (radiating upwards ordownwards). In vertical arrangements, due to the heat rising, the burneris warmer at the top than at the bottom, whereby the infra-red radiationbecomes non-uniform. This results in it being impossible to set thedesired wavelength on the infra-red emitter.

2. Difficulties to obtain an even high intensity at the same time asbeing able to adapt the wavelength in the infra-red spectrum todiffering areas of application.

3. Inadequate efficiency. When the gas pressure and thereby thethrough-flow speed for the gas increases, the flames try to separatefrom the burner with the result that the heat emission to the infra-redradiating element reduces. The result is that convection heat increasesand the infra-red radiation decreases.

SUMMARY OF THE INVENTION

With the invention, a gas powered burner has been achieved for emittinginfra-red radiation. Due to the possibilities of adjustment of theinfra-red radiating burner element, the burner is relatively insensitiveto placement or position.

The burner element is intended to emit radiation within the infra-redspectrum, containing energy of sufficient intensity for industrial usesuch as for instance heating up solid or liquid material, drying oforganic or inorganic material as well as hardening of, for example,paints or glue in so-called infra-red chambers or the like.

The invention can also advantageously be used for grills for grilling offood products since it can be placed vertically and thereby can give anodor free cooking of the raw products requiring most heat.

The construction of the burner according to the present invention isintended for all types of flammable gas. It is built up from two or moreperforated plates or fire proof ceramic material. By displacing the twoplates closest to the back part and which lie in contact with eachother, symmetrical or asymmetrical hole patterns and hole geometries canbe set up. This permits the gases which flow through the plates to beable to be directed in different directions. In addition to this, theconstruction allows the hole width to be able to be adjusted uniformlyor asymmetrically in a continual throttling of the gas supply from oneedge to the other. The construction of the burner permits the combustionchambers in and between the perforated ceramic plates, in principal, tobe adjusted during operation. This means that the drawbacks, whichresults in uneven combustion and difficulties to keep all the emittedradiation within the desired wave-length in the infra-red spectrum,which occur when known gas powered infra-red radiators are placedvertically, can be removed via adjustment with this invention.

By placing one or more ceramic plates, perforated with holes, outsideand at a suitable distance from the inner plate combination, acombustion chamber is achieved. This combustion chamber can be closed orprovided with throttle valves for supply air. Should one use supply airto the chamber, automatic ignition and cut-out should be placed there.The supply air can occur passively or actively by the use of fans. It ismainly this outer plate or plate combination which constitutes theinfra-red radiating element in the burner. By using two or more platesit is possible to achieve slanted or curved through-bore geometries.This means that the length of the through-bore which is createdincreases in relation to perpendicular holes whilst using the samethickness of burner element. This in turn implies that the heatabsorbing surface on the infra-red radiating element increase withrespect to if it was perforated by holes arranged at right angles. Thisrelationship increases the efficiency.

The clay material included in the ceramic elements can be chosen suchthat the infra-red wavelength band is emitted at different temperatures.By a careful choice of ceramic material, the intensity within eachwavelength can be controlled. The ceramic burner elements can bemanufactured in plane or curved shapes and can be pressed or cast indifferent sizes.

A vertically placed gas powered infra-red radiator, as previouslymentioned, always tends to be warmer at the top than at the bottom. Tocounteract this, the gas outlet can be directed downwardly and/orthrottled successively from the lower outlet to the upper. In thismanner a uniformity in the combustion and thereby the temperature can bemaintained over the burner elements whole surface independently of theplacing and the position of the burner. Additional, perforated platescan be added, the ceramic composition and the structure of which can bevaried.

The burners according to the present invention are couplable together tolarge infra-red radiation units which, due to the burners'adjustability, can be constructed in many different ways. The burnerscan be put together in a laying or standing circle or respectively ahalf-circle shape and can even form complete radiation walls where eachseparate burner, independently of the placing in the group, can beoptimized with regard to the wavelength and intensity emitted.

The invention can be illustrated by the burners being placed in a grillfor grilling of food products, the resultant grill being particularlysimple to maintain and which gives a very good grilling result for manydifferent types of raw products. The characteristics of the burneraccording to the invention are defined in the appended claims.

Further scope of applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention shall now be described in more detail with reference tothe accompanying drawings, in which

FIG. 1 shows a vertical section through a part of the burner accordingto the invention;

FIG. 2 shows the burner in FIG. 1 in an exploded view seen from thefront;

FIG. 3 shows the burner according to the invention from the side,coupled together according to one embodiment;

FIG. 4 shows another embodiment of the present invention;

FIG. 5 shows the hole width decreasing with height by displacement oftwo perforated plates; and

FIG. 6 shows a variation of the burner with five perforated plates.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The construction is, of course, not limited to the embodiments which areshown and described, but can be varied in many ways within the scope ofthe following claims. This concerns not only the number of burners 1 butalso their relative location, along with the number of perforatedceramic plates 3, 3a, 3b included in each burner 1 and their appearanceregarding the shape of the holes 2, 2a, 2b.

The main component of the arrangement is a gas powered burner 1, thebasic form of which includes plates 3 of ceramic material perforated byholes 2. The shown embodiment comprises three plates 3, 3a and 3b, eachprovided with holes 2, 2a, 2b. The plates are placed in a frame 7 with adistance 8 between the outer periphery of the plates and the innerperiphery of the frame. Frame 7 is further provided with openings 9 toallow the supply of oxygen to one or more combustion chambers 5.

A conduit 4 is attached to the burner 1 to provide a supply of gas.After being ignited, the gas warms up the perforated plates 3, 3a, 3b tored-hot temperature, whereby infra-red radiation is transmitted, saidradiation being of a comparatively high frequency and thereby effective.

The holes 2, 2a, 2b can be round, three-, four-, five-, or six-sided orcan have another shape for forming a pattern. Each of the plates 3, 3a,3b is displaceable in its plane. In this way the ceramic lattice work ofthe three plates 3, 3a, 3b obtains holes with different opening widthsin different regions. Thus the amount of gas flowing through the latticework can be regulated to achieve the optimum effect.

As far as possible, the combustion should occur inside the lattice work.In order to prevent the combustion from reducing to an undesirably lowlevel due to insufficient oxygen, the plates can conveniently be movedapart. FIG. 1 shows the plate 3b moved a little from the plate 3a forforming an air-gap 5 between these plates. In this way the oxygen supplyto the combustion zone can be resulted and at the same time it can beensured that the combustion occurs entirely inside the lattice work sothat the energy content of the gas is absorbed to a maximum by theplates 3, 3a, 3b. The plates which lie in contact with the combustionarea will hereby start to become red-hot and the outermost plate 3bemits energy in the form of infra-red radiation. The wavelength and theintensity are dependent on the energy supplied and the choice ofmaterials for the burner elements. The wasted energy which flows outinto the air is hereby negligible and the burner 1 thus functions veryeconomically.

In order to avoid that the combustion zone, due to unfavorableadjustment of the plates 3, 3a, 3b, moving into the space behind theplates, this space is suitably filled up with any mineral wool, filtermaterial 6 or the like. This material firstly presents an explosive typecombustion of the gas, but at the same time provides a uniformdistribution of the gas over the rear side of the lattice work.

Due to the fact that the plates are relatively adjustable, the burner 1can be attached upright and meat juices from food products willtherefore never contact the burners' surface, but instead they willtravel down towards to the bottom plate. In this way no smell occurs.

The ignition of the gas can occur in a conventional manner using matchesor fire lighters but it can also occur using a more sophisticatedtechnique, such as for example a piezo-electric manner. An automaticignition system of this type can conveniently be placed in theintermediate space between the flow-limiting plate combination and theheat radiating plate/plates combination. A combustion monitoring cut-outcan also be placed in this intermediate space. FIG. 3 shows acombination of three burners placed close to each other and with a gasconduit 4 connected to each one of the burners.

We claim:
 1. A gas powered burner for emitting infrared radiation,comprising:a gas supply means for supplying gas to said gas poweredburner; oxygen supply means for supplying oxygen to said gas poweredburner; a housing connected to said gas supply means and having a backpart; at least tow ceramic plates adjacent to said housing, each ceramicplate having a plurality of perforations therein, said at least twoceramic plates lying in parallel with each other and being mutuallyadjustable relative to each other; means for supplying said at least twoceramic plates and for adjusting a position of one of said at least twoceramic plates relative to one another and thereby adjusting acombustion chamber in and between said at least two ceramic plates;wherein said at least two ceramic plates constitute an infraredradiating element with radiation which is variable due to mutualadjustment of said at least two ceramic plates.
 2. The gas poweredburner according to claim 1, wherein said at least two ceramic platesare separable from each other for formation of at least one air spacethere between so as to control supply of oxygen to the burner.
 3. Thegas powered burner according to claim 1, wherein the at least twoceramic plates include at least three ceramic plates, said at leastthree ceramic plates being placed group wise with at least opensubstantially flow-controlling plate combination placed closest to saidback part of said burner and additionally an outer, substantiallyradiation-emitting plate placed at a distance from the flow-controllingplate combination in order to form an air gap.
 4. The gas powered burneraccording to claim 3, wherein automatic ignition and ignition cut-outare located in said air gap.
 5. The gas powered burner according toclaim 1, wherein upon relative displacement of the ceramic plates,through-holes in the ceramic plates are formed having varying geometryin their longitudinal section, whereby the available energy absorbingsurface area for a ceramic plate is varied.
 6. The gas powered burneraccording to claim 1, wherein the ceramic plates are placed in a frame,which is provided with openings to allow a supply of oxygen to at leastone combustion chamber and, at the same time, allow the possibility ofadjusting air introduction so as to ensure that combustion of gas occursfully inside the burner so that the maximum energy content of the gas isabsorbed by the ceramic plates.
 7. The gas powered burner according toclaim 6, wherein the frame for containing the ceramic plates, is largerthan an outer perimeter of the back part, whereby the heat emission fromthe plates (3) to the metal frame is limited and an adjustment operationfor the ceramic plates is easier to carry out.
 8. The gas powered burneraccording to claim 7, wherein a space between an outer periphery of theceramic plates and an inner periphery of the frame is filled with aresilient, insulating fireproof material.
 9. The gas powered burneraccording to claim 1, wherein said back part is filled with filtermaterial.
 10. The gas powered burner according to claim 1, whereinautomatic ignition and ignition cut-out are located in front of theceramic plates.